Gloss calender



June 22, 1965 A. MOORE 3,190,212 GLOSS GALENDER Original Filed Dec. 1. 1961 Fig.1

mvsm'ok. Zak/fence flayaafas Maare BY 2% fim, w b/4w A TTORNE YS Unitcd States Patent This application is a continuation of .my copending application Serial No; 156,258,'filed December 1, 1961,

. now abandoned.

A principal object of the invention is to improve upon the calendering of paper webs by providing improved means for heating certain of the rolls of a gloss calender.

Another and important object of the invention is to provide a new and improved method and apparatus for increasing the speed of calendering by, heating the finishing roll more rapidly and at highertemperatures than has heretofore been possible.

Another object of the invention is to provide an improved form of means for heating certain of the rolls of a gloss calender by impinging heated air along the surfaces of certain of the rolls and controlling the application of heated air to the rolls to selected zones across the width of the rolls to increase the speed of calendering and to maintain predetermined profiles of'the rolls for caliper control. 7

Still another object of the invention is to improve upon the calendering of paper webs by heating the finishing and pressure rolls of the calender to higher temperatures than formerly and zoning the distribution of heat over the surfaces of the rolls.

Still another object of the invention is to improve upon the calendering of paper webs -by providing an improved means for more rapidly heating the surfaces of certain of the rolls of a calender stack, readily adaptable to various conventional calenders with little or no substantial modification in construction of the calenders,

The calender herein shown is conventionally used to calender uncoated paper as it leaves the drier of a paper making machine, but may also calender sized printing grades of paper or board grades of paper, and by the heating system of the present invention, the calender rolls may be heated more rapidly and at much higher temperatures than formerly, and the application of heat to the rolls may be zoned to maintain the rolls to the required profile for caliper control.

These and other objects of the invention will appear from time to time as the following specification proceeds and with reference to the accompanying drawings wherein:

FIGURE 1 is a diagrammatic view of a gloss calender stack constructed in accordance with the principles of the present invention; and

FIGURE 2 is a diagrammatic view of an air distribution and heating hood, illustrating the manner in which the heated air may be zoned along the surface of a roll of a calender stack. i a

In the embodiment of the invention illustrated in FIG- URE l of the drawings, I have shown a calendar stack 10 for finishing a web of paper W, which may be uncoated paper or plasticized coated paper, in which finishing or glossing is attained by the process of pressing the fibers of the web to the web, and in effect ironing the Web as it leaves the drier. a

As diagrammatically shown in FIGURE 1 of the draw ings, the calender includes alower large diameter finish-v ing roll 11, commonly called a king roll. Spaced above the roll 11 and in hip defining relation with respect thereto is a roll 12 which may have a resilient face, made from rubber or any other material, providing a hard but resilient surface. f

The finishing roll 11 is a driven roll and may be driven from a suitable source of power in a conventional manner (not shown) and may have a plated surface, plated with chrome or nickel, to provide a highly polished surface for glossing treatment. The rubber faced roll 12 is driven by contact with the web W and the finishing roll 11, although it may be positively driven, if desired.

In diametrical alignment with the rolls 11 and 12 are two pressure rolls 15 and 16 driven by contact with the web andthe roll 12. The rolls 15 and 16 may be also hard surfaced rolls and may be made from cast iron or any other suitable material, and serve to level out the web and thereby control the caliper of thesweb. The pressure rolls 15 and 16 may be loaded hydraulically or pneumatically in a conventional manner, to hold the exacting nip pressures, which pressures may be controlled automatically in accordance with the condition of the.

web being run, in a conventional manner.

In conventional calenders, the finishing roll' has been heated internally by steam to temperatures high enough to bring the outer surface of .the roll substantially to the temperature of-the boiling point of water. Where the roll is heated by steam, the temperature to which the outersurface of the roll may be heated is-limited principally by limitations in thickness of the finishing roll, the face of which must be thick enough to withstand the heavy pressure of calendering.

Ithas been found, however, that the finishing roll 11 may advantageously be heated to far higher temperatures than the boiling point of water and that a better calendering etfect is attained at these temperatures, by impinging heated air directly on the finishing'roll. This increases the speed of calendering'and not only improves the finishing of the paper, but the distribution of heat along the surface of the roll may be controlled to maintain the roll to the required profile, with the resultant better caliper control of the paper.

In accordance with the principles of the present invention, I am able to attain these temperatures with a reduced heating time by the use of a drier hood 17 wrapped partially about the periphery of the finishing roll 11, and impinging air heated to high temperatures directly on the surface of said finishing roll.

As for example, 'for a wrap lof a drier hood. of substantially 156 about the finishing roll 11, and the impingement of air at a temperature of 600 F. on the surfaced the finishing roll '11, the temperature of the surface of the finishing roll may be maintained at 450 F.

,The wrap required to maintainthe temperature of the surface of the finishing roll 11 at 400 F. with air at a temperature of 600 is substantially 108", while the wrap required to maintain the temperature of the finishing roll 11 at 350 withan air temperature within the hood of 600 is substantially 76.

In FIGURE 1, I have diagrammatically shown a fan 19 forcing air through a heater 20 into the hood 17 through an intakeduct 21. The fan 19 may withdraw spent .air from the surface of the finishing roll 11 and recirculate the air through an exhaust duct 22. Fresh air may also be drawn into the fan 19 through an intake duct 23 under the control of a damper 24.

The hood or-.air cap may be of a type similar to that, shown and described in application Serial No, 152,836, filed by Edgar I. Justus and Lawrence A. Moore on November 16, 1961 and entitled Drier Hood Construction and assigned to ,the'assignee of the present is supplied with heated air under pressure.

forate bottom 25, under the control of airinlet valves hip between the rolls 11 and 12 to, keep the finishing roll clean. The top pressure roll 15 has a doctor blade 30 mounted at its outr'unning side to keep theroll clean and to prevent the web W from running" up said'rolliThe doctor-blade'30 is shown as extending from aidrier hood 31,.wrapped partially abouttheroll 15, for heating the surface o f said roll by the impingement of' heated air thereonto in a manner similar to'which the surface of the roll 11 is heated. The drier hood 31 may be constructed v on principles similar to the drier hood 11 and-may be:

zoned across the width thereof,' togenable, theidistribution of heated air across the width 0f the roll to 'be 'controlled, to give the required profile yto the roll 15jf01 caliper control. The drier hood 31 has an intake duct 32 least 75? and for substantially the full width of the finishwhich may be supplied with heated air under pressure in the same manner the intake duct 21 of the drierhood 17 The top pressure roll 16 is also shown as having adrier zoned like the drier hoods 17 and31, not only to heat the pressure roll 16, but also to givesaid pressure roll the proper profile for caliper control. Adoctor blade 35 extends from the drier hood 3310 the surface of the hood 33 partially wrapped ther'eabout,nwhich may beri roll 16, at the outgoing side of the nip between the rolls 15 and 16,-'to keep theroll '16 clean and to prevent the paper web from running up roll 16.

The web W thus passes through the nip between the pressure rolls 15 and 16, which serve to level otf the paper 7 7 web to theproper thickness.

The web W is then wrapped partially-about the roll 15 and passes in the nip betweenthe rolls 12' and 15 around'a direction changing idler 36 spaced laterally of the roll 12. r The web then changes'its direction about said idler and passes in the nip between the, rolls 11 and 12, which serves to finish .the'web to the required glossby ironing the web as it passes through the nip between said rolls. a i i It maybe seen from the foregoing that a new method of tures than formerly by impinging air overa substantial which also makes it possible to distribute the heat to the rolls in zones along the Widths of the rolls, to maintain therolls to'the proper profile and to thus attain a better caliper control of the web, with'aaresultant more uniformly I finished product, with less waste'than formerly. 7

It may further be seen that the heating means may be adapted'for various types of calendars and makes it pos- .1 a a V 4; faceof the vfinishing roll to the boiling point of water and at the incoming side ofthe nip between the finishing roll and the backing roll'by impinging heated air on the surface of the finishing roll,

. and along a circumferential areathereof of at least 75 and thereby heating the surface of the finishing roll tov a temperature in the-orderyof 350 F.

3. A method of calendering an uncoated paper web i as it leaves the drier of a paper, making machinegcompris- 'ing the passing of the web through the nips of a series of pressure-rolls and through the nip betweena backing roll and'a finishing roll of'a calender stack, wrapping a drier'hood'about the finishing roll; at the incoming side of the nip between the finishing roll and the'backi'ng roll 1 along a circumferential surface of the finishing roll of at and thereby heating the surface of the finishing roll to as it passes the drierof a paper making machine coma prising the passing of the web through 'thenipsfof'a series of pressure rolls and through the nip between; a, backing roll and a finishing roll of a calender, stack,

heating the surfaces of the' pressure rolls-at the incoming sides of the nips therebetween to temperatures substan-x tially greater than the boiling point of water by impinging t heated air thereon overfa substantial area thereof, and

heatingthe surface of the finishing roll at the incoming side of the nip between the finishing roll and thetbacking roll to a temperature substantially greater than the boil- 7 ing'point of water by impingingheated air, on the surface of the finishing roll over a substantial area thereof. 5. A-method of calendering an 'uncoated paper web asit' leaves the drier of a paper making machine 'iniac cordance with claim 4 in which drier hoods are partially calendering paper webs'has been provided by more rapidly heating the rolls of a calender stack tohigher tempera- 0 sible to reduce the cost and speed of calenderingand at r the same time to providea more accurate caliper control of the web and a better final product; 1 w

While I have herein shownand described one form; in which my invention may be embodied, it may readily be understood thatvarious variations and modifications in the invention maybe attained without departing from the spirit and scope of thenovel conceptsthereofl a I claim as my-invention: 1

1.- A method of calendering jan uncoatedpaper'webas it leaves the drier of a papermaking machine, comprising 7 the passing of the web through the nips of aseriesof pres-' sure rolls and throughthe'nip between-abacking roll and a finishing roll pi e calender'stack, and heating the surwrapped about the pressure rolls at' the incoming side of the nips therebetween and a drier hood is partially, wrapped about the finishing rollat the incoming .sideof. I

the nip between the finishing roll and the backing roll,

wherein the hoods are wrapped about the. finishingand; 'pressureflrolls for at least 75 and whereinithe. hoodsj';

impinge air heated to a temperature substantially 600 on the finishing roll and pressure 'rolls for substantially the areas covered by said hoods and thereby 'heatthe surfaces of the finishing roll and pressure rolls to tem= peratures in the order of 350; 7 t a a 6. A calender comprising a bottom finishing roll having a hard finishing surface, a vertically spaced backing roll having a resilient surface in nip definingrelation with I respect to said finishing roll, pressure "rolls above said backing roll in nip' defining relation with respect to said backing roll, and in nip defining relation with respect to each otherymeaus guiding a paper web to pass between thetnips defined by said pressure rolls and said backing roll and finishing. roll, and, means for heating the surface of said finishing roll to a temperature above the boilingpoint of water to thereby increase the speediofcalendering, comprising a hood extending for theiwidth of said finishing roll and having an air impingement SUI? face partially wrapped about said finishing roll on the.

incoming side of-the nip between'said finishing roll and. said' backing roll for at least 607 and extending for substantially the Width of said finishing roll," a blower forcing heated air through said hood and thereby/impinging a temperature greater than heated air through said air impingement surface directly on the surface of said finishing rollover a substantial area of the roll. 7

7. A calender comprising a'bottom finishing roll having a hard finishing surface, a vertically spaced backing roll in nip defining relation with respect to said finishing roll, pressure rolls above said backing roll in nip definand a connection from said blower to said hood, f0rcing heated air through said hood and out through said air impingement surface directly on the surface of said finishing roll, said drier hood being zoned to enable the distribution of heated air across the width of said finishing roll to be controlled over a substantial area of the roll and to thereby control the profile of said finishing roll.

8. A calender comprising a bottom finishing roll having a hard finishing surface, a vertically spaced backing roll having a resilient surface in nip defining relation with respect to said hard finishing surface of said finishing roll, pressure rolls above said backing roll in nip defining relation with respect to said backing roll and in nip defining relation with respect to each other, means guiding a paper web to pass between the nips defined by said pressure rolls and said backing roll and finishing roll, and means for increasing the speed of calendering and thereby facilitating the calendering operation comprising a drier hood having an air impingement surface extending for the width of said finishing roll and about said finishing roll on the incoming side of the nip between said finishing roll and said backing roll for at least means supplying heated air at a order of 600 F., and a blower having communication with said hood and forcing heated air from said air supplying means through said air impingement surface onto the surface of said finishing roll for the full area of said'air impingement surface. 7

9. In -a calender stack, a lower finishing roll having a hard finishing surface, a backing roll in nip defining relation with respect to said finishing roll, a pair of top pressure rolls in nip defining relation with respect to each other, the lowermost of said pressure rolls being in nip defining relation with respect to said backing roll, and means for increasing the speed of calendering and thereby facilitating the calendering operation comprising a dryer hood extending substantially the width of one of said pressure rolls and having an air impingement surface wrapped about said roll and extending about said roll for a substantial area, means for forcing the heated air through said air impingement surface onto said pressure roll, and a second dryer hood having an air impingement surface wrapped partially about said finishing roll on the incoming side of the nip between said finishing roll ,and backing roll and means for supplying the air heated to a temperature of at least 600 and forcing air through said air impingement surface onto the surface of said finishing roll'and thereby heating the surface of said finishing roll to a temperature greater than the boiling point of water,

References Cited by the Examiner UNITED STATES PATENTS 737,571 9/03 Bray -93 1,291,626 1/19 Parks 100-38 1,423,969 7/22 Schurmann 100163 1,700,267 1/29 Kneeland 100-93 2,993,432 7/61 Youngchild 100-93 WALTER A, SCHEEL, Primary Examiner.

temperature on the 

1. A METHOD OF CALENDERING AN UNCOATED PAPER WEB AS IT LEAVES THE DRIER OF A PAPER MAKING MACHINE, COMPRISING THE PASSING OF THE WEB THROUGH THE NIPS OF A SERIES OF PRESSURE ROLLS AND THROUGH THE NIP BETWEEN A BACKING ROLL AND A FINISHING ROLL OF A CALENDER STACK, AND HEATING THE SURFACE OF THE FINISHING ROLL TO A TEMPERATURE GREATER THAN THE BOILING POINT OF WATER AND AT THE INCOMING SIDE OF THE NIP BETWEEN THE FINISHING ROLL AND THE BACKING ROLL BY IMPINGING HEATED AIR ON THE SURFACE OF THE FINISHING ROLL OVER A SUBSTANTIAL AREA THEREOF. 